The long-term objectives of this proposed research are to determine the genetic and antigenic basis for the diversity of spotted fever group rickettsiae in eastern Asia. This knowledge is the foundation for the development of a rational epidemiologic and immunologic approach to development of effective preventive vaccines and diagnostic tools for these rickettsioses. Important aspects of this proposal are the active participation of leading rickettsiologists of the People's Republic of China as visiting scholars at the University of North Carolina to learn molecular rickettsiologic techniques and the work in the field, hospitals, and laboratories of the People's Republic of China by the American principal investigator. This combination of opportunities offers the prospect of opening the knowledge of this important geographic area to modern scientific access. Isolators of spotted fever group rickettsiae from China including Jing-he rickettsia and Rickettsia sibirica will be compared with R. sibirica from the USSR and other Asian spotted fever group rickettsiae such as R. conorii, JC-880, and TT-118. Methods which will be employed include microimmuno-fluorescent antibody analysis, Western immunoblotting, monoclonal antibodies, and restriction endonuclease analysis of rickettsial DNA. North Asian tick typhus is a widespread spotted fever group rickettsiosis of public health importance in China, USSR, and Mongolia. India tick typhus and Southeast Asian spotted fever group rickettsioses border upon China but are of unknown distribution within the People's Republic of China. A major interest of the principal rickettsiology laboratory in China, located at the National Center for Preventive Medicine in Beijing, is spotted fever group rickettsioses of China. This research proposal offers the fulfillment of long-term cooperative aggreement with that laboratory and the elucidation of the ecology and molecular rickettsiology of spotted fever rickettsiae in China which will be subsequently carried forward by the Chinese scientists.